Electrical generator sets supply electrical power in remote locations or in locations where access to standard utility power is unavailable. Generator sets can also provide a source of back-up energy in the event of a utility power failure. Some generator sets are sized such that they can be moved from one place to another. Such portable generator sets generally consist of an internal combustion engine coupled to a synchronous alternator or a direct-current (“DC”) generator.
Traditionally, the engine of a generator set has to operate at a constant speed, regardless of the load, to provide a usable source of power. The constant operation of the engine can cause extra noise to be generated and fuel to be used, even when the actual usage of power from the generator set is light (or even unloaded).